A Serious New Pest is Causing Significant Problems for Dendrobium and Hibiscus Growers
L.S. Osborne, E.R. Duke, T.J. Weissling, J.E. Pena, and D.W. Armstrong.

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In 1995 a paper was published reporting the occurrence of newly reported pest in North America. This pest, Contarinia maculipennis Felt small fly that was first found attacking Dendrobium spp. in Apopka (collected: November 12-16, 1992) and Miami (collected: August 1993). Prior to this report it was known from Hawaii where it attacked buds of hibiscus, tomato and jasmine. Since that time the number of people reporting problems with premature bud drop has greatly increased. According to the January 1997 Newsletter of the Sunset Chapter-American Hibiscus Society, the Schermerhorns first found them after they dissected some of the aborted hibiscus buds.

When infested orchid buds were examined 5-30 small white fly larvae were found. Once these larvae are fully developed they drop to the soil were they are eventually burrow into the soil and pupate. Adults emerge in about 3 weeks depending on temperature. One interesting behavior the helps in this pests identification is their ability to jump or spring several centimeters. When an infested hibiscus buds are placed in a plastic vegetable storage bag, fully developed larvae begin to emerge within a day. When the larvae are removed from the bag and placed on a dark flat surface you will notice they begin to "flip" themselves significant distances.

Control tactics have not been fully investigated. What we do know however is that many of the nurseries that make regular applications of pesticides for whiteflies have not reported a problem. To be effective at managing this pest you must practice sanitation by removing all dropped buds or buds on the plant that are beginning to mold. Secondly, because the larvae enter the soil to pupate, pesticide applications to the soil could prove beneficial. In the Newsletter the authors suggested the regular application of Orthene or Cygon to the foliage/buds and soil applications of Dursban or Diazinon. THERE ARE NO OFFICIAL RECOMMENDATIONS FOR THE CONTROL OF THIS PEST. However, the following LINKS to the pesticide recommendations for ornamental pests contain lists of materials that are registered for the management of soil inhabiting and leaf mining flies on other crops. Chemical control evaluations will begin as soon as colonies are established.

Biological control tactics for Contarinia maculipennis need to be investigated. Biological control of other gall midges, such as the citrus midge (Prodiplosis longifila), has proven to be effective at greatly reducing the impact of these serious pests.  

Figure 1: Infested hibiscus blossoms.  Note larvae at the tip and to the left of the paint brush.

Figure 2: Larva that has just exited the infested bud to pupate in the soil.

Figure 3: A close up view of the same larva.

Figure 4: Another magnified view of a larva. This is probably the only stage of this pest that you will observe!


Figure 5: A magnified view of the adult.

 Photographs by L.S. Osborne and J.E. Pena.
  The genus Contarinia contains a number of species that attack flowers. Many form galls and are relatively host specific. The following Links are to the Institut National de la Recherche Agronomique (INRA) site in France that details the biology of a few important species from this genus. They are included because there are some very nice photographs of adults flies. These adults are quite similar in appearance to the species we are concerned with.

To view an INRA
drawing of the Lucerne
Flower Midge click here.
To view an INRA
photograph of a Lentil
Flower Midge click here
To view an INRA
photograph of the Pear
midge laying an egg in a
pear click here.

L.S. Osborne, Ph.D.
University of Florida
Central Florida Research and Education Center
2807 Binion Road
Apopka, FL 32703
(407)884-2034, lso@icon.apk.ufl.edu
E.R. Duke, Ph.D. & T.J. Weissling, Ph.D.
University of Florida
Ft. Lauderdale Research and Education Center
J.E. Pena, Ph.D.
Tropical Research and Education Center
18905 SW 280 St.
Homestead, FL 33031
D.W. Armstrong
University of Florida and
Pinellas County Cooperative Extension Service
12175 125th St. N.
Largo, FL 33774